Circumdatins D, E, and F:  Further Fungal Benzodiazepine Analogues from Aspergillus ochraceus

Abstract

Three new benzodiazepine alkaloids belonging to the circumdatin series have been isolated as minor constituents of culture extracts of a terrestrial strain of the fungus Aspergillus ochraceus. Their structures were solved by MS and NMR comparison with previously reported circumdatin analogues.

Enterotoxicity of a nonribosomal peptide causes antibiotic-associated colitis

“…Values are means ± SEM, two-tailed Student t test. *P < 0.05. the exception of pentacyclic PBDs that have been isolated from marine Aspergilli (44,45). The origin of the genomic island carrying the tilivalline biosynthetic genes would thus seem to be phylogenetically distant.…”

Circumdatin I, a New Ultraviolet-A Protecting Benzodiazepine Alkaloid from a Marine Isolate of the Fungus Exophiala

“…Thus, 1 was characterized as 5,15-dihydroxycircumdatin F [5] on the basis of direct comparison of NMR data of 1 with those of 2 and 3. The absolute stereochemistry of 1 was investigated using CD.…”

Circumdatin H, a New Inhibitor of Mitochondrial NADH Oxidase, from Aspergillus ochraceus

“…The isolation and structure characterization of a novel benzodiazepine, circumdatin H (1), as a minor constituent of A. ochraceus culture broth is reported, together the known benzodiazepine circumdatin E (2) [8], the pyrazinone flavacol (3) [10,11] and the alkaloid stephacidin A (4) [2]. The structure of 1 was determined by comparison of its 1 H NMR and 13 C NMR spectral data (Table 1) with those of other known circumdatins, especially 2, and was confirmed by 2D NMR experiments (COSY H-H, HSQC and HMBC) [7,9].…”

“…Compound 2 was identified as circumdatin E by comparison of its spectral data with the literature [8]. All data of compound 3 were coincident with flavacol [10,11].…”

“…circumdatin (1), with three other known alkaloids (2ϳ4) [2,8,10,11], is reported. All of these alkaloids were assayed as inhibitors of integrated electron transfer chain, due to their structural analogies with well-known inhibitors of the respiratory chain [12,13].…”